Ink, ink-jet recording method, and instrument employing the ink

ABSTRACT

An ink comprises a recording agent and a liquid medium for dissolving or dispersing the recording agent, the ink comprising a compound represented by the general formula (I) or (II): ##STR1## where R 1  and R 2  are independently selected from the group consisting of radicals of hydrogen, alkyl or alkoxy having not more than 10 carbons, sulfonic acid or salts thereof, nitro, hydroxyl, carboxyl, and amino or derivatives thereof, and R 1  and R 2  are not simultaneously hydrogen radical. The ink is suitable used for ink-jet recording.

This application is a continuation, of application Ser. No. 07/664,111filed Mar. 4, 1991, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ink, an ink-jet recording methodemploying the ink, and an instrument employing the ink. Moreparticularly, the present invention relates to an ink, an ink-jetrecording method, an ink-jet recording unit, an ink-jet recordingapparatus, and an ink cartridge which allow recording in high resolutionand high quality not only on coated paper prepared specially for ink-jetrecording but also on non-coated ordinary paper generally used inoffices and homes such as copying paper, reporting paper, notebookpaper, letter paper, bond paper, continuous business form paper, and thelike.

2. Related Background Art

Various compositions of inks have been reported for ink-jet recording.In recent years, research and development are comprehensively conductedregarding inks from various aspects of compositions and physicalproperties of inks for the purpose of achieving satisfactory recordingon ordinary paper such as copying paper, reporting paper, notebookpaper, letter paper, bond paper, continuous business form paper, and thelike.

Conventional inks contain generally a high-boiling organic solvent likeglycol for retardation of premature drying and prevention of clogging ofink. If such an ink is used for recording on highly sized ordinarypaper, the ink does not readily permeate into the interior of paper anddoes not dry rapidly, which causes insufficient fixation of ink, andwhich in inconveniences such as staining of a finger and blurring orscratching of letters upon touching a recorded matter.

To offset the inconvenience, Japanese Patent Application Laid-Open No.55-29546 discloses a method of adding a large amount of surfactant tothe ink to increase permeability of ink into the interior of paper. Inthis case, however, troubles are encountered such as frequent occurrenceof running or feathering of ink depending on the kind of paper; andretardation of ink ejection in ink-jet recording caused by backwardmovement of ink from the orifice-outlet face, or wetting of the entireorifice-outlet face depending on the structure of the head.

Further, Japanese Patent Application Laid-Open No. 56-57862 discloses amethod of making the pH of ink strongly alkaline. Such an ink isdisadvantageous in that the ink is dangerous to humans when touched witha finger and the ink is unsatisfactory in occurrence of feathering andinsufficiency of drying property on paper employing a certain kind ofsizing agent, e.g. neutralized paper.

In spite of the aforementioned and other improvements, no ink is knownthat is free from the problems of feathering, lack of drying property,danger to humans, and occurrence of clogging and so forth.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an ink that provides isfree from the problems feathering of ink and delayed drying of recordedmatters, and which gives high quality of printing on non-coated paper orordinary paper such as copying paper, reporting paper, notebook paper,letter paper, bond paper, continuous business form paper, etc. that isgenerally used in offices and elsewhere. Further objects include anink-jet recording method and an ink-jet apparatus employing the ink.

Another object of the present invention is to provide an ink for ink-jetprinting that is sufficiently safe for use in offices and homes.

A further object of the present invention is to provide an ink that doesnot tend to clog nozzles of ink-jet heads and is highly reliable.

According to an aspect of the present invention, there is provided anink comprising a recording agent and a liquid medium for dissolving ordispersing the recording agent, the ink comprising a compoundrepresented by the general formula (I) or (II): ##STR2## where R₁ and R₂are independently selected from the group consisting of radicals ofhydrogen, alkyl or alkoxy having not more than 10 carbons, sulfonic acidand salts thereof, nitro, hydroxyl, carboxyl, and amino or derivativesthereof, and R₁ and R₂ are not simultaneously hydrogen radical.

According to another aspect of the present invention, there is providedan ink-jet recording method of conducting recording by ejecting inkdroplets through an orifice onto a recording medium in response to arecording signal, wherein the above-mentioned ink is employed.

According to still another aspect of the present invention, there isprovided a recording unit having an ink container portion for holding anink and a head portion for ejecting the ink in droplets, wherein theabove-mentioned ink is employed.

According to a further aspect of the present invention, there isprovided an ink cartridge having an ink container portion for holding anink, wherein the above-mentioned ink is employed.

According to a still further aspect of the present invention, there isprovided an ink-jet recording apparatus having an ink container portionfor holding an ink and a head portion for ejecting the ink in droplets,wherein the above-mentioned ink is employed.

According to a still further aspect of the present invention, there isprovided an ink-jet recording apparatus having a recording head forejecting ink in droplets, an ink cartridge having an ink containerportion for holding ink, and an ink-supplying portion for supplying inkfrom the ink cartridge to the recording head, wherein theabove-mentioned ink is employed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A and FIG. 1B are respectively a vertical cross-sectional view anda lateral cross-sectional view of a head portion of an ink-jet recordingapparatus.

FIG. 2 is an exterior oblique view of a multiplicate form of the head ofFIG. 1.

FIG. 3 is an oblique view of an ink-jet recording apparatus.

FIG. 4 is a vertical cross-sectional view of an ink cartridge.

FIG. 5 is an oblique view of a recording unit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The inventors of the present invention have made comprehensiveinvestigations with respect to compositions of inks to preventfeathering of ink and to improve drying property and permeablility ofink on ordinary paper. Consequently, the inventors found that the inkcontaining the compound represented by the general formual (I) or (II)shown above is well-balanced in feathering and permeation of the ink,being not adversely affected in anti-clogging property, and beingreliable without causing a problem in safety, and have accomplished thepresent invention.

According to the investigation of the inventors regarding feathering andpermeation of ink on ordinary paper, an ink containing a surfactant asemployed in conventional inks does not give invariably stable recordingdepending on the kind of paper, while an ink containing the compoundrepresented by the general formula (I) or (II) gives highlysatisfactorily stable recording independent of the kind of paper.

The reason is considered to be that the feathering and the permeation ofink greatly affected by a wetting phenomenon at the interface between anink droplet and paper. The wetting property of an ink containing awetting agent at the surface portion of the ink droplet differs fromthat in the interior of the ink droplet, giving unsatisfactory results.The ink of the present invention does not tend to cause such phenomenon,and moreover, the ink of the present invention has exquisitelywell-balanced affinity with a sizing agent added to the surface orinterior of paper, as an ink for ink-jet for ordinary paper.

The present invention is described in more detail by reference to apreferred embodiment.

The compounds represented by the general formula (I) or (II) shown aboveare derivatives respectivley, of benzyl alcohol or of cyclohexanol, andare obtainable by known methods.

Specific examples of R₁ and R₂ of the compounds represented by thegeneral formula (I) and (II) are shown below. The present invention isnot limited to these specific examples. In the following table, R₁ is atthe para-position and R₂ is at an ortho-position relative to thehydroxyl group.

    ______________________________________                                        Compound example No.                                                                             R.sub.1   R.sub.2                                          ______________________________________                                        1                  CH.sub.3  H                                                2                  C.sub.2 H.sub.5                                                                         H                                                3                  C.sub.3 H.sub.7                                                                         H                                                4                  C.sub.4 H.sub.9                                                                         H                                                5                  C.sub.9 H.sub.19                                                                        H                                                6                  OCH.sub.3 H                                                7                  OC.sub.2 H.sub.5                                                                        H                                                8                  OC.sub.3 H.sub.7                                                                        H                                                9                  CH.sub.3  CH.sub.3                                         10                 CH.sub.3  C.sub.2 H.sub.5                                  11                 OH        H                                                12                 NH.sub.2  H                                                13                 COOH      H                                                14                 NHCOCH.sub.3                                                                            H                                                15                 OH        CH.sub.3                                         16                 NO.sub.2  H                                                17                 SO.sub.3 Na                                                                             H                                                18                 C.sub.2 H.sub.5                                                                         C.sub.2 H.sub.5                                  ______________________________________                                    

The compounds represented by the above general formula (I) or (II)employed in the present invention are derived as a result ofcomprehensive study by selecting R₁ and R₂. The compounds having analkyl or alkoxy group having 11 or more carbons as R₁ or R₂, forexample, causes problems in feathering although it gives satisfactorypermeability, and are remarkably inferior to the compounds of thegeneral formula (I) or (II) in various properties.

The amount of addition of the compound of the general formula (I) or(II) is within the range of from 0.01% to 30% by weight, preferably from0.1% to 10% by weight, more preferably from 0.2% to 5% by weight of theink depending on a coloring matter used and a liquid medium componentcombinedly used.

The ink of the present invention is characterized by the compoundrepresented by the general formula (I) or (II) contained thereintogether with a coloring matter. Additionally the ink of the presentinvention may contain combinedly water and ordinary organic solventwhich are used in known conventional inks. The organic solvent includesalkyl alcohols having 1 to 5 carbons such as methyl alcohol, ethylalcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butylalcohol, tert-butyl alcohol, isobutyl alcohol, n-pentanol, etc.; amidessuch as dimethylformamide, dimethylacetamide, etc.; ketones andketoalcohols such as acetone, diacetone alcohol etc.; ethers such astetrahydrofuran, dioxane, etc.; oxyethylene or oxypropylene additionpolymers such as diethylene glycol, triethylene glycol, tetraethyleneglycol, dipropylene glycol, tripropylene glycol, polyethylene glycol,polypropylene glycol, etc.; alkylene glycols having an alkylene group of2 to 6 carbons such as ethylene glycol, propylene glycol, trimethyleneglycol, butylene glycol, 1,2,6-hexanetriol, hexylene glycol, etc.;thiodiglycol; glycerin; lower alkyl ethers of a polyhydric alcohol suchas ethylene glycol monomethyl (or monoethyl) ether, diethylene glycolmonomethyl (or monoethyl) ether, triethylene glycol monomethyl (ormonoethyl) ether, etc.; lower dialkyl ethers of a polyhydric alcoholsuch as triethylene glycol dimethyl (or diethyl) ether, tetraethyleneglycol dimethyl (or diethyl) ether, etc.; sulfolane,N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, and the like.

The content of the water-soluble organic solvent is generally within therange of from 2% to 50% by weight, preferably 2% to 30% by weight basedon the total weight of the ink.

The above mediums may be used singly or mixedly. The preferablecomposition of the liquid medium is a combination of water and one ormore organic solvents, the organic solvents containing at least onewater-soluble high-boiling organic solvent, for example, a polyhydricalcohol such as diethylene glycol, triethylene glycol, glycerin, etc.,and the like.

The recording agent constituting the ink of the present inventionincludes direct dyes, acid dyes, food dyes, basic dyes, reactive dyes,disperse dyes, vat dyes, soluble vat dyes, reactive disperse dyes, oilydyes, and various pigments. Among them, water-soluble dyes areparticularly preferable in view of properties of the ink.

The content of the coloring matter is determined depending on the kindof liquid medium constituent, performances required to the ink, and soforth. Generally the content is in the range of from about 0.2% to 20%by weight, preferably from 0.5% to 10% by weight, more preferably from1% to 5% by weight of the entire ink.

The main constituents of the ink of the present invention are asdescribed above. Supplementarily, a dispersant, a surfactant, aviscosity-adjusting agent, a surface tension-adjusting agent, afluorescent whitener, or the like may be added as an auxiliary additiveto the ink, if necessary, within the range of not adversely affectingthe object of the present invention.

The examples of the auxiliary additives are viscosity-adjusting agentssuch as polyvinyl alcohol, cellulose derivatives, water-soluble resins,etc.; various surfactants of cationic, anionic, and nonionic type;surface tension-adjusting agents such as diethanolamine,triethanolamine, etc.: pH-adjusting agents of buffer solution;mildewproofing agents, and the like.

Further, in preparation of an ink for ink-jet recording of anink-electrification type, there is added a resistivity-adjusting agentsuch as inorganic salts including lithium chloride, ammonium chloride,sodium chloride, etc.

The ink of the present invention is particularly suitable for ink-jetrecording of the type of ejecting ink by bubbling of ink caused bythermal energy, in which the ink is ejected extremely stably withoutforming satellite dots. For this use, the thermal properties (such asspecific heat, thermal expansion coefficient, thermal conductivity,etc.) may be adjusted.

Further, the ink of the present invention is adjusted desirably to have,as properties of ink itself, a surface tension in the range of from 30to 68 dyne/cm at 25° C., and viscosity of not higher than 15 cP,preferably not higher than 10 cP, more preferably not higher than 5 cPso as to solve the problems of feathering, delayed drying, andinsufficient permeation in recording on ordinary paper, as well as toimprove matching of the ink with the ink-jet head.

In order to control the property of the ink as above to solve problemsencountered on ordinary paper, the ink of the present invention containswater preferably in an amount of from 50% to 98% by weight, morepreferably from 60% to 95% by weight, still more preferably from 75% to95% by weight.

The ink of the present invention, which is employed particularlysuitably for an ink-jet recording method for recording by ejecting inkdroplets by thermal energy, is naturally useful also for general writingutensils.

The methods and the apparatus suitable for the use of the ink of thepresent invention are those which provides thermal energy to ink in acell in a recording head in correspondence with recording signals toform liquid droplets by the thermal energy.

An example of the constitution of the heads, which is a main portion ofthe apparatus, is shown in FIG. 1A, FIG. 1B, and FIG. 2.

A head 13 is formed by bonding a plate of glass, ceramics, or plasticshaving a groove 14 for ink passage with a heat-generating head 15. Thetype of the head is not limited to the one shown in the figure. Theheat-generating head 15 is constituted of a protection layer 16 formedof silicon oxide or the like, aluminum electrodes 17-1 and 17-2, aheat-generating resistance layer 18 formed of nichrome or the like, aheat accumulation layer 19, and a substrate plate 20 having goodheat-releasing property made of alumina or the like.

Ink 21 reaches to the ejection orifice 22 (a fine pore), forming ameniscus 23 by action of pressure P not shown in the figure.

On application of an electric signal to the electrodes 17-1 and 17-2,the region designated by a symbol "n" on the heat-generation head 15abruptly generates heat to form a bubble in the ink 21 at the positionadjacent thereto. The pressure generated by the bubble pushes out themeniscus 23 and ejects the ink 21, as recording droplets 24, and the inkdroplets are propelled to a recording medium 25. FIG. 2 illustrates amulti-head construction by juxtaposing a multitude of heads shown inFIG. 1A. The multi-head is prepared by bonding a glass plate 27 having amultitude of grooves 26 with a heat-generation head 28 similar to theone described in FIG. 1A.

Incidentally, FIG. 1A is a cross-sectional view of the head 13 along anink flow path, and FIG. 1B is a cross-sectional view of the head at theline I-II in FIG. 1A.

FIG. 3 illustrates an example of the ink-jet recording apparatusincorporating such a head mounted therein.

In FIG. 3, a blade 61 as a wiping member is held at its one end by ablade-holding member, forming a fixed end in a shape of a cantilever.The blade 61 is placed at a position adjacent to the recording region ofthe recording head, and in this example, is held so as to protrude intothe moving path of the recording head. A cap 62 is placed at a homeposition adjacent to the blade 61, and is constituted such that it movesin the direction perpendicular to the moving direction of the recordinghead to come into contact with the ejection nozzle face to cap thenozzles. An ink absorption member 63 is provided at a position adjacentto the blade 61, and is held so as to protrude into the moving path ofthe recording head in a manner similar to that of the blade 61. Theaforementioned blade 61, the cap 62, the ink absorption member 63constitute an ejection-recovery portion 64, the blade 61 and the inkabsorption member 63 remove water, dust, and the like from the inkejecting nozzle face.

A recording head 65 has an ejection energy generation means forejection, and conducts recording by ejecting ink toward a recordingmedium opposing to the ejection nozzle face having ejection outletsarranged thereon. A carriage 66 is provided for supporting and movingthe recording head 65. The carriage 66 is engaged slidably with a guiderod 67. A portion of the carriage 66 is connected (not shown in thefigure) to a belt 69 driven by a motor 68, so that the carriage 66 ismovable along the guide rod 67 to the recording region of the recordinghead 65 and the adjacent region thereto.

The constitution of a paper delivery portion 51 for delivery of arecording medium and a paper delivery roller 52 driven by a motor notshown in the figure delivers the recording medium to the positionopposing the ejecting nozzle face of the recording head, and therecording medium is discharged with the progress of the recording topaper discharge portion provided with paper-discharge rollers 53.

In the above constitution, the cap 62 of the ejection-recovery portion64 is out of the moving path of the recording head 65 when the headreturns to the home position upon termination of recording, etc, whilethe blade 61 is made to protrude into the moving path. Therefore, theejecting nozzle face of recording head 65 is wiped therewith. The cap 62moves to protrude toward the moving path of the recording head when thecap 62 comes into contact for capping with the ejecting nozzle face ofthe recording head.

At the time when the recording head 65 moves from the home position tothe record-starting position, the cap 62 and the blade 61 are at thesame position as in the above-mentioned wiping time, so that theejection nozzle face of the recording head is wiped also in thismovement.

The recording head moves to the home position not only at the end of therecording and at the time of ejection recovery, but also at apredetermined interval during movement for recording in the recordingregion. By such movement, the wiping is conducted.

FIG. 4 illustrates an example of the ink cartridge containing ink to besupplied through an ink supplying member such as a tube. The inkcontainer portion 40, for example an ink bag, contains an ink to besupplied, and has a rubber plug 42 at the tip. By inserting a needle(not shown in the figure) into the plug 42, the ink in the ink containerportion 40 is accessed. An absorption member 44 absorbs waste ink.

The ink container portion has preferably a liquid-contacting face madeof polyolefin, especially polyethylene as in the present invention.

The ink-jet recording apparatus used in the present invention is notlimited to the above-mentioned one which has separately a head and anink cartridge. Integration thereof into one body as shown in FIG. 5 maysuitably be used.

In FIG. 5, a recording unit 70 houses an ink container portion such asan ink absorption member, and the ink in the ink absorption member isejected from a head 71 having a plurality of orifices. The material forthe ink absorption member is preferably polyurethane as in the presentinvention.

Air-communication opening 72 is provided to communicate the interior ofthe cartridge with the open air.

The recording unit 70 may be used in place of the recording head shownin FIG. 3, and is readily mountable to and removable from the carriage66.

The present invention is described in more detail referring to examplesand comparative examples. The units "part" and "%" in the descriptionare based on weight unless otherwise mentioned.

EXAMPLES 1-5

The components below were mixed and stirred for 5 hours. The pH of themixture was adjusted to 7.5 by adding aqueous 0.1% sodium hydroxidesolution, and filtered under pressure through a membrane filter having apore size of 0.22 μm, thereby the inks A to E of the present inventionbeing prepared.

The resulting inks A to E were used for recording on commercial copyingpaper and bond paper by means of an ink-jet printer BJ-130 (trade name,made by Canon K. K.), which employs heat generating elements as anink-ejecting energy source. The level of the fixation and occurrenceratio of feathering (feathering ratio) of the recorded matters,occurrence of clogging at restart of printing after intermission ofprinting, and frequency responsiveness were evaluated. The results areshown in Table 1.

    ______________________________________                                        Ink A                                                                         C.I. Direct Yellow 86    2       parts                                        Diethylene glycol        15      parts                                        Compound example 1 of general formula (I)                                                              1.2     parts                                        Water                    81.8    parts                                        Ink B                                                                         C.I. Acid Red 35         2       parts                                        Glycerin                 10      parts                                        Compound example 6 of general formula (I)                                                              1.8     parts                                        Ethylene glycol          5.5     parts                                        Water                    80.7    parts                                        Ink C                                                                         C.I. Food Black 2        3       parts                                        Triethylene glycol       10      parts                                        N-methyl 2-pyrrolidone   2       parts                                        Compound example 2 of general formula (I)                                                              1.2     parts                                        Water                    83.8    parts                                        Ink D                                                                         C.I. Direct Blue 199     2.5     parts                                        Polyethylene glycol (molecular weight 300)                                                             5       parts                                        Diethylene glycol        10      parts                                        Triethylene glycol monomethyl ether                                                                    2       parts                                        Triethanolamine          0.5     part                                         Compound example 14 of general formula (I)                                                             3.5     parts                                        Water                    76.5    parts                                        Ink E                                                                         C.I. Direct Black 154    2       parts                                        Thiodiglycol             6       parts                                        Diethylene glycol        9       parts                                        Compound example 9 of general formula (I)                                                              1.2     parts                                        Water                    81.8    parts                                        ______________________________________                                    

COMPARATIVE EXAMPLES 1-4

The inks F to I of Comparative examples 1 to 4 were prepared from thecomponents below, and evaluated in the same manner as in Examples 1 to5. The results are show in Table 1.

    ______________________________________                                        Ink F                                                                         C.I. Direct Yellow 86    2       parts                                        Diethylene glycol        15      parts                                        Water                    83      parts                                        Ink G                                                                         C.I. Food Black 2        3       parts                                        Diethylene glycol        10      parts                                        Triethylene glycol       10      parts                                        Nonionic surfactant (trade name: Nissan Nonion                                P223, made by Nippon Oil and Fats Co, Ltd.)                                                            0.5     parts                                        Water                    76.5    parts                                        Ink H                                                                         C.I. Acid Red 35         2       parts                                        Glycerin                 10      parts                                        Compound of general formula (I)                                                                        1.8     parts                                        (R.sub.1 = C.sub.11 H.sub.23, R.sub.2 = H)                                    Ethylene glycol          5.5     parts                                        Water                    80.7    parts                                        Ink I                                                                         C.I. Food Black 2        3       parts                                        Triethylene glycol       10      parts                                        N-methyl-2-pyrrolidone   2       parts                                        Ethanol                  1       part                                         Water                    84      parts                                        ______________________________________                                    

                  TABLE 1                                                         ______________________________________                                        Example No.     1      2       3    4     5                                   ______________________________________                                        Ink             A      B       C    D     E                                   Fixation*.sup.1                                                               Copying paper   ⊚                                                                     ⊚                                                                      ⊚                                                                   ◯                                                                       ◯                       Bond paper      ⊚                                                                     ⊚                                                                      ⊚                                                                   ⊚                                                                    ⊚                    Feathering ratio*.sup.2                                                       Copying paper   ◯                                                                        ◯                                                                         ◯                                                                      ◯                                                                       ◯                       Bond paper      ◯                                                                        ◯                                                                         ◯                                                                      ◯                                                                       ◯                       Clogging*.sup.3 ◯                                                                        ◯                                                                         ◯                                                                      ◯                                                                       ◯                       Frequency responsiveness*.sup.4                                                               ⊚                                                                     ⊚                                                                      ⊚                                                                   ⊚                                                                    ⊚                    ______________________________________                                        Comparative example No.                                                                       1      2       3    4                                         ______________________________________                                        Ink             F      G       H    I                                         Fixation*.sup.1                                                               Copying paper   X      ⊚                                                                      ⊚                                                                   .increment.                               Bond paper      .increment.                                                                          ⊚                                                                      ⊚                                                                   ◯                             Feathering ratio*.sup.2                                                       Copying paper   ◯                                                                        X       X    ◯                             Bond paper      ◯                                                                        X       X    ◯                             Clogging*.sup.3 .increment.                                                                          X       .increment.                                                                        X                                         Frequency responsiveness*.sup.4                                                               X      X       .increment.                                                                        .increment.                               ______________________________________                                         *.sup.1 Evaluation of fixation:                                               Ten seconds, and 30 seconds after the printing on commercial copying pape     and bond paper, the printed portion was rubbed with filter paper (No. 5C:     trade name, made by Toyo Roshi K.K.). The fixation was graded as below.       The evaluation was conducted at 25° C. and 60% RH.                     ⊚: Not blurred after 10 seconds,                               ◯: Slightly blurred after 10 seconds,                             .increment.: Slightly blurred after 30 seconds,                               X: Remarkably blurred after 30 seconds.                                       *.sup.2 Feathering ratio:                                                     300 dots were printed discontinuously by a printer on commercial copying      paper and bond paper. After one hour or more, the printed dots were           examined with a microscope to count the number of dots which exhibited        feathering. The ratio of occurrence of feathering was graded as below         according to the percentage of the feathering dots relative to the total      dots in number. The printing was conducted at the environmental condition     of 25° C. and 60% RH.                                                  ◯: 10% or less,                                                   .increment.: 11 to 30%,                                                       X: 31% or more.                                                               *.sup.3 Clogging:                                                             "Clogging" means a clogging tendency at restart of printing after             intermission of printing. The ink to be tested was filled to the printer,     and printing of alphabets and numerals was conducted continously for 10       minutes. After the printer was left standing for ten minutes without          capping the nozzles, the same printing was restarted. The clogging was        graded according to the presence or absence of blurring and defects of th     printed letters at the restart of the printing.                               The evaluation was conducted at 25° C. and 60% RH.                     ◯: The first letter being not defective,                          .increment.: The first letter being partially blurred or defective,           X: The first letter not being printed out.                                    *.sup.4 Frequency responsiveness:                                             The printed state of the printed matter, namely blurring, white blank,        splashing, distortion, or the like of the letters resulting from the          failure of the inkshooting was observed visually, and was graded as below     ⊚: The response of the ink to frequency being satisfactory     No blurring, white blank, nor incorrect shooting being observed in both       solid printing and character printing.                                        ◯: The response of ink to frequency being almost satisfactory     No blurring, white blank, nor incorrect shooting being observed in            character printing, but slight blurring being observed in solid printing.     .increment.: No blurring nor white blank being observed and partial           incorrect inkshooting being observed in character printing. Blurring and      white blank being observed in onethird of the whole solid printing area.      X: Blurring and white blank being significant in solid printing, and          blurring and incorrect inkshooting being remarkable.                     

EXAMPLES 6-10, AND COMPARATIVE EXAMPLE 5

The inks J to N of the present invention and the ink O of Comparativeexample were prepared from the components below in the same manner as inExample 1. The inks were evaluated in the same manner as in Example 1.The results are shown in Table 2.

    ______________________________________                                        Ink J                                                                         C.I. Direct Yellow 86    2       parts                                        Diethylene glycol        15      parts                                        Compound example 1 of general formula (II)                                                             1       part                                         Water                    82      parts                                        Ink K                                                                         C.I. Acid Red 35         2       parts                                        Glycerin                 10      parts                                        Compound example 6 of general formula (II)                                                             1.5     parts                                        Ethylene glycol          5.5     parts                                        Water                    81      parts                                        Ink L                                                                         C.I. Food Black 2        3       parts                                        Triethylene glycol       10      parts                                        N-methyl-2-pyrrolidone   2       parts                                        Compound example 2 of general formula (II)                                                             1       parts                                        Water                    84      parts                                        Ink M                                                                         C.I. Direct Blue 199     2.5     parts                                        Polyethylene glycol (molecular weight 300)                                                             5       parts                                        Diethylene glycol        10      parts                                        Triethylene glycol monomethyl ether                                                                    2       parts                                        Triethanolamine          0.5     part                                         Compound example 16 of general formula (II)                                                            3       parts                                        Water                    77      parts                                        Ink N                                                                         C.I. Direct Black 154    2       parts                                        Thiodiglycol             6       parts                                        Diethylene glycol        9       parts                                        Compound example 9 of general formula (II)                                                             1       parts                                        Water                    82      parts                                        Ink O (Comparative example 5)                                                 C.I. Acid Red 35         2       parts                                        Glycerin                 10      parts                                        Compound of general formula (II)                                                                       1.5     parts                                        (R.sub.1 = C.sub.11 H.sub.23, R.sub.2 = H)                                    Ethylene glycol          5.5     parts                                        Water                    81      parts                                        ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                                                  Comparative                                                  Example          example                                                      6    7      8      9    10   5                                       ______________________________________                                        Ink        J      K      L    M    N    O                                     Fixation*.sup.1                                                               Copying paper                                                                            ⊚                                                                     ⊚                                                                     ⊚                                                                   ◯                                                                      ⊚                                                                   ⊚                      Bond paper ⊚                                                                     ⊚                                                                     ⊚                                                                   ⊚                                                                   ⊚                                                                   ⊚                      Feathering ratio*.sup.2                                                       Copying paper                                                                            ◯                                                                        ◯                                                                        ◯                                                                      ◯                                                                      ◯                                                                      X                                     Bond paper ◯                                                                        ◯                                                                        ◯                                                                      ◯                                                                      ◯                                                                      X                                     Clogging*.sup.3                                                                          ◯                                                                        ◯                                                                        ◯                                                                      ◯                                                                      ◯                                                                      .increment.                           Frequency  ⊚                                                                     ⊚                                                                     ⊚                                                                   ⊚                                                                   ⊚                                                                   .increment.                           responsiveness*.sup.4                                                         ______________________________________                                    

As described above, the ink of the present invention enables recordingwith high quality without blurring and with satisfactory fixation onordinary paper such as copying paper, reporting paper, notebook paperletter paper, bond paper, continuous business form paper, etc. generallyused in offices and elsewhere.

Further, the present invention provides an ink that is highly safe inuse in offices and homes.

Furthermore, the present invention enables reliable ink jet recordingwithout occurrence of clogging of an ink-jet nozzle, and in particularremarkably improves responsiveness of ink ejection in recording methodsutilizing bubbling of ink by thermal energy for ink ejection.

The use of the ink of the present invention also increases thereliability of printing apparatus.

What is claimed is:
 1. An ink comprising a recording agent and anaqueous liquid medium for dissolving or dispersing the recording agent,the ink comprising a compound represented by the general formula (I) or(II): ##STR3## where R₁ and R₂ are independently selected from the groupconsisting of radicals of hydrogen, alkyl or alkoxy having not more than10 carbons, sulfonic acid or salts thereof, nitro, hydroxyl, carboxyl,and amino or derivatives thereof, and R₁ and R₂ are not simultaneously ahydrogen radical, and wherein said compound is contained in an amount inthe range of from 0.01% to 30% by weight of the total weight of the ink.2. The ink of claim 1, wherein the ink contains water and awater-soluble organic solvent as the liquid medium.
 3. The ink of claim2, wherein the content of water is in the range of from 50% to 98% byweight of the total weight of the ink.
 4. The ink of claim 2 wherein thecontent of said water-soluble organic solvent is in the range of from 2%to 50% by weight of the total weight of the ink.